It wasn’t just that Louis van Gaal’s streak of four straight wins over his club’s bitterest rivals came to an end, it was the manner of the defeat. United was thoroughly outplayed in the 2-0 loss to Liverpool in their Europa League last-16 first leg. United was grateful to David De Gea for keeping the score down, and, while it’s not inconceivable that the deficit–the result of a Daniel Sturridge penalty and another goal from Roberto Firmino–can be made up at Old Trafford next week, it would take a radically improved performance even to be possible.

This was a game that was always going to reverberate beyond its immediate context. Not only was this the first meeting in European competition of England’s two most successful sides, both domestically and in European terms, it has come at a rare time when pre-eminence in the Liverpool-United rivalry is uncertain.

Perhaps between 1990, Liverpool’s last league title, and 1993, United’s first under Alex Ferguson, as the pendulum swung east along the M62, supremacy was blurred, but essentially the story of English football since the early 1970s has been a 20-year period of Liverpool dominance followed by a 20-year period of United dominance.

With Ferguson retired, United’s hegemony is over and the question is whether Jurgen Klopp, young, dynamic and charismatic, can take advantage of United’s uncertainty. Even if Van Gaal does retain his job next season, something that seemed implausible three weeks ago but has become possible again thanks to progress in the Europa League and FA Cup, he is extremely unlikely to stay on beyond the end of his present contract, which expires in the summer of 2017.

His departure will inevitably bring further uncertainty and that means that, for all its financial advantages, United is vulnerable for the first time in years.

Before the match, Klopp had described it as “the mother of all games” and amid a ferocious atmosphere it gave some idea of its scale that former United players Gary Pallister, Andy Cole and Denis Irwin were stood together in the away end. They could not have enjoyed what they saw.

Liverpool controlled the game from the offset and went ahead after 20 minutes, with Philippe Coutinho stabbing a pass through for Nathaniel Clyne, on a surge from right back. Memphis Depay reacted late, had a panicked grab at his shirt and conceded a penalty that Sturridge gleefully dispatched.

With United rocking, Liverpool could have scored three more before halftime. De Gea made an extraordinary save from Coutinho as he made an oddly tame attempt to turn Sturridge’s cross/shot in at the back post. A slip from Chris Smalling presented Sturridge with another chance, only for the forward to blast his shot into De Gea’s thigh, before the keeper was drawn into a reflex save as Adam Lallana met Roberto Firmino’s cross with a first-time shot.

United, it must be acknowledged was undone by injuries and by the suspension to Jesse Lingard that led to the 18-year-old Marcus Rashford, scorer of four goals in his first two games for United from center forward, being deployed on the right, trying to track the forward surges of Alberto Moreno. Anthony Martial, presumably, would have taken on that role had it not been for the need to play him at center forward, an indication of the scattered approach to transfers that has left United without adequate cover in that area.

Rashford was presented with a great chance inside 15 seconds as a cross from the left evaded Moreno, but, seemingly startled that the ball had reached him–and perhaps unsighted–he let the ball cannon off his knees. Thereafter he had a miserable night, tracking uncomfortably up and down the right flank in an unfamiliar role, unable to impose himself and withdrawn at halftime.

Michael Carrick came on for him as United switched to a back three which worked in the sense that it checked Liverpool’s flow. It could not entirely stem it, though. De Gea made another excellent save to keep out a Coutinho drive but the second goal was coming and eventually arrived 17 minutes from time. A wretched Carrick clearance fell for Lallana who square for Firmino to steer in his eighth goal in his last 13 games.

That sealed a comprehensive victory, but it also confirmed an emerging pattern, one that is extremely troubling for United. Liverpool, having conceded just two goals in its last seven games, looks as though it is beginning to absorb Klopp’s message. He will make changes in the summer, but the basic structure is starting to emerge. And while Liverpool is on the up, United, three years after Ferguson’s abdication, still looks like a club in search of a plan.